Diode rectifier



W. R. KOCH DIODE RECTIFIER May 9, 1939.

Filed NOV. 30, 1936 Patented May 9, 1939 UNITED STATES PATENT DIODE RECTIFIER tion of Delaware Application November 30, 1936, Serial No. 113,474

'7 Claims.

The present invention relates to a diode rectifier for ultra high frequency signals, and has for its object to provide a rectifier for that purpose which permits a light load on the tuned circuit through which signals are applied to the diode rectifier, and a correspondingly higher applied voltage, without appreciably reducing the selectivity of said tuned circuit.

It is a further object of the present invention to provide a diode rectifier for ultra high frequency signals such as modulated carrier wave signals, whereby the diode may have a relatively low current carrying capacity and corresponding relatively small anode and cathode elements, and, at the same time, to provide a relatively low impedance output circuit for the modulation component of a received signal.

In carrying out the objects of the invention, a direct current feed-back amplifier is provided in connection with a diode rectifier, for supplying a major portion of a bias potential for the diode. The invention will, however, be better understood from the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, the figure is a schematic circuit diagram of a diode rectifier for ultra high frequency signals embodying the invention.

Referring to the drawing, an ultra high frequency input circuit 5 is coupled to a diode rectifier device 6 through a suitable tuned coupling transformer I, the tuned secondary circuit 8 of which forms the diode circuit for developing an input potential at the carrier wave frequency across the circuit terminals 9 and Ill.

The high potential terminal of the input circult is connected with the diode anode II, and the cathode l2 of the rectifier is connected through a diode output resistor l3, an amplifier output resistor l5 and a potential source 15, to the low potential terminal Ill of the input circuit. The last named connection between the potential source and the terminal I0 is provided by a circuit lead it in connection with a variable contact H for adjusting the potential derived from the source l5. This may be provided in any suitable manner, and in the present example is provided by a potential divider resistor I8, of which the portion I5 forms a part and to which a direct current potential is supplied through leads l9 and 20, the latter being grounded and being the negative lead.

The potential source IS, in series between the cathode and the low potential terminal H] of the input circuit, provides an initial positive biasing potential on the diode anode II with respect to the cathode I2, which may be adjusted in value by means of the contact ET in connection with the resistor l8.

The direct current component of signals re- 5 ceived through the rectifier 6 across the diode output resistor 13, is applied to a direct current amplifier tube indicated at 2 l between input electrodes comprising a control grid 22 and cathode 23, connected, as shown, across the output resistor l3 of the diode rectifier. The grid is con nected through a. lead 24 with the cathode or positive end 25 of the diode output resistor, while the cathode 23 of the amplifier is connected through a lead 26 with the negative terminal 21 of the diode output resistor H3.

The terminal 21 is also the junction between the diode output resistor 13 and the amplifier output resistor l4, and the latter is included in the anode circuit of the amplifier 2! through its connection with the negative lead 20 which forms the cathode return lead from the potential supply source l8. The anode circuit is completed from the positive lead l9 through a lead 28 to the anode 29 of the amplifier 2|.

Between the cathode 23 and the lead 26, a self-bias resistor 30 is provided to establish between the grid 22 and the cathode 23, an initial low negative biasing potential for the grid in the absence of received signals, whereby the grid is prevented from drawing current.

It will be seen that this circuit arrangement causes the grid 22 to receive an increasingly positive biasing potential with respect to the cathode 35 23 in response to received signals. The initial anode current through the return circuit, including the resistor I4, is increased to raise the potential of the terminal 21 to a higher positive value above ground at the same time that the diode anode II is raised to a higher positive potential above ground by the received signal or carrier wave.

The contact I! is adjusted to provide an initial diode biasing potential in the diode circuit, in the absence of applied high frequency signals, so thatv no current flows in the resistor l3 and the voltage between the low potential terminal ill of the input circuit and the high potential or output terminal 21 of the amplifier 25 are equal positive potentials with respect to ground.

An initial biasing potential is provided in the diode circuit so that the potential across the resistor l4 resulting from plate current of the tube 2| and. the potential across the resistor section I 5 are caused to balance each other.

If the diode anode H were made more positive than the cathode, current would flow even in the absence of signals, whereas in the balanced condition of the potentials above referred to, no current flows in the resistor l3 and the voltages at the terminals I! and 2! are equal positive potentials with respect to ground 2|].

When a voltage is applied to the input circuit 5 from a received modulated carrier wave, the direct current voltage developed between the cathode and anode of the diode rectifier will become substantially equal to the peak applied alternating current or signal voltage. The diode current flow through the output resistor l3 will cause the grid of the triode or diode amplifier 2i to become more positive, thus increasing the anode current through the output resistor l4 and also the self-bias resistor 30, and therefore making the junction or output terminal 21 more positive with respect to ground, as above pointed out.

With a resistor l3 of substantially l megohm, and a resistor M of approximately 10,000 ohms, it has been found that substantially of the increase in voltage may be caused to occur at the junction terminal 21 between the two resistors l3 and i4, and only 20% of the increase may occur across the resistor I3. The diode current through the output resistor [3 of the diode may therefore be reduced to substantially one-fifth of that which would normally flow in the usual diode circuit, without the current amplifier 2|. The diode may therefore be substantially one-fifth the size of that which would otherwise be necessary. In connection with high frequency tuned circuits, this permits higher impedance, lower load, and higher output potentials.

An audio frequency output circuit impedance may be connected across the low impedance output resistor M in the amplifier circuit between ground and the lead 28. Because of the low impedance of the output circuit, a transformer or other low impedance coupling means may be provided as indicated at 3|, between the output circuit of the amplifier and a suitable utilization device such as an audio frequency amplifier tube 32. The latter is provided with the usual output circuit, indicated at 34, from which amplified signals may be derived in any suitable and well known manner.

However, any utilization device may be connected between the output lead 26 and ground to receive the amplified output from the diode rectifier, and this may be at direct current or audio frequency currents, for the reason that the modulation component of the signal in the diode output resistor appears, with the direct current or plate current variations, across the low impedance output circuit provided by the output resistor 14.

Because of the small diode current required in the system as shown, the tuned input circuit 8, supplying input potential to the diode, is loaded to a much lower degree and the applied input voltage may therefore be higher, while the selectivity of the tuned circuit may be greatly increased over that normally provided in connection with a diode rectifier.

From the foregoing description, it will be seen that the diode rectifier system, as shown and described, provides, in effect, a diode rectifier circuit in which the output resistor between the cathode and the low potential side of the input circuit is connected in series with means providing a variable direct current potential having a polarity such that the variable voltage is in series-aiding relation to the voltage developed by the signal across the diode output resistor, and, in response to received signals, causes the cathode potential above ground to rise in proportion to the rise in potential on the diode anode resulting from reception of a carrier wave, whereby a major portion of the peak signal voltage in the diode input circuit is established across the variable potential source. In this manner, the voltage between the diode anode and the cathode is maintained at a relatively small percentage of the peak input voltage, thereby reducing the diode output current proportionately and permitting a diode rectifier of relatively small size.

In addition, the variable voltage producing means, in series with the diode output resistor between the negative end thereof and the ground or low potential side of the diode input circuit, is included in the output circuit of a direct current amplifier having its control grid connected with the positive or cathode end of the diode output resistor and having its cathode connected to the junction point between the terminal of the diode output resistor and the variable voltage source, whereby the latter may be provided by a resistor effectively in the anode output circuit of the amplifier in the cathode return lead thereof.

With this arrangement, it has been found that with an initial adjustment of the voltage derived across the resistor section i5 providing a biasing potential for the diode anode, positive with respect to ground, equal in amount to the positive potential on the diode cathode represented by the potential at the terminal 21, an applied signal having a peak of 11 volts across the terminals 0 and H] of the input circuit may provide a potential of one volt across the output resistor i3 which provides a ten volt increase on the amplifier resistor M. This indicates the relatively low output current which is required to be delivered through the output rectifier to the output resistor l3, resulting in higher permissible input impedances for the rectifier circuit, sharper tuning, and lower effective output impedances for connection with utilization circuits.

I claim as my invention:

1. In a diode rectifier circuit, the combination with a diode rectifier device, of means providing an output impedance therefor, and means for maintaining the signal output potential across said impedance below a predetermined value in response to variable signal energy applied to said circuit, said means comprising a source of biasing potential providing a positive potential on the anode of the diode rectifier device with respect to a fixed reference point on said circuit and a variable source of positive bination, a signal input circuit, a diode rectifier device having an anode electrode connected to the high potential side of said circuit and having a cathode, a diode output resistor connected between said cathode and the low potential terminal of said input circuit, means providing a variable potential source in said connection for the diode output resistor in series-aiding relation to signal potentials developed across said output resistor, and means for controlling said last named means in response to variations in signal potential received on said input circuit to increase the potential of said source with increases in said signal potential.

3. A diode rectifier circuit for ultra high frequency modulated signals adapted to utilize a rectifier of relatively low current carrying capacity thereby to provide a low degree of loading upon a signal supply means, said circuit comprising in combination, a high impedance tuned signal input circuit, a diode rectifier device having an anode electrode connected to the high potential side of said circuit and having a cathode, a diode output resistor connected between said cathode and the low potential terminal of said input circuit, means providing a variable potential source in said last-named connection for the diode output resistor in series-aiding relation to signal potentials developed across said output resistor, and means for controlling said last named means in response to variations in signal potential received on said input circuit to increase the potential of said source with increases in signal potential.

4. A diode rectifier circuit for ultra high frequency signals, comprising in combination, a high impedance tuned signal input circuit, a diode rectifier device having an anode electrode connected to the high potential side of said circuit and having a cathode, a diode output resistor connected between said cathode and the low potential terminal of said input circuit, and means providing a variable potential source in said connection in series-aiding relation to signal potentials developed across said output resistor, a direct current amplifier tube having a control grid connected with the cathode end of the diode output resistor and having an anode circuit resistor connected adjacent to said output resistor as said variable potential source, and means in circuit between the diode anode and said last named resistor for establishing on said diode anode a positive potential substantially equal to a positive potential established on said diode cathode by said amplifier output resistor, in the absence of received signals.

5. A diode rectifier for ultra high frequency signals comprising, in combination, a high impedance tuned input circuit having high potential and low potential terminals, a diode rectifier having an anode electrode connected with the high potential terminal and having a cathode, a diode output resistor connected between the cathode and ground, an electric discharge amplifier device having a control grid connected to the cathode end of said output resistor and having a cathode connected with the negative end of said output resistor, an anode output resistor for said amplifier connected between said negative end of the diode output resistor and ground whereby an initial positive potential with respect to ground is established on the diode cathode, means for establishing a fixed initial positive biasing potential with respect to ground on the diode anode, and a utilization circuit coupled to said anode output resistor of the electric discharge amplifier device.

6. A diode rectifier system for utilizing high frequency signals comprising, in combination, means providing a high impedance tunable input circuit for received ultra high frequency signals, a diode rectifier connected therewith and having anode and cathode elements providing a relatively low capacity in connection with said circuit, and means for limiting the output current of said rectifier in the presence of received signals comprising a high impedance output resistor for said rectifier, a direct current amplifier tube having a control grid connected with the positive end of said resistor and having a cathode connected with the negative end thereof, means for applying a positive anode potential to said amplifier having a negative cathode return connection with the negative end of said diode output resistor and including an anode output resistor of relatively low impedance with respect to the impedance of the diode output resistor, means for applying a fixed initial negative biasing potential to the control grid of said amplifier, and means for applying a fixed initial positive biasing potential to the anode of said diode rectifier.

7. A diode rectifier circuit comprising in combination, a signal input circuit, a diode rectifier device having an anode electrode connected to the high potential side of said circuit and having a cathode, a diode output resistor connected between said cathode and the low potential terminal of said input circuit, means providing a variable potential source in said connection in series-aiding relation to signal potentials developed across said output resistor, and means for controlling said last named means in response to variations in signal potential received on said input circuit to increase the potential of said source with increases in said signal potential, said last named means including a direct current amplifier tube having a control grid connected with the cathode end of the diode output resistor and having an anode circuit resistor connected adjacent to the diode output resistor as said variable potential source.

R. KOCH. 

